Diaphragm and piston pumps are used to supply metered quantities of liquids with various properties. Depending on the field of application, the pump behaviour is subject to various requirements in order to ensure that the delivered quantity of the metered medium is as precise as possible and remains constant for as long as possible.
Diaphragm pumps are common industrial pumps that use positive displacement to move liquids. These devices typically include a single diaphragm and chamber, as well as discharge check valves to prevent back-flow. Pistons are either coupled to the diaphragm or used to force hydraulic oil to drive the diaphragm. Diaphragm pumps are normally highly reliable because they do not include internal parts that rub against each other. Diaphragm pumps can handle a range of media that includes abrasive materials, acids, chemicals, or the like since the drive means is normally completely separated from hydraulic part of the pump. Since diaphragm pumps can deliver small volumes of fluid with the maximum discharge, they are especially suitable as dosage pumps.
Another reason for using diaphragm pumps as dosage pumps is that these pumps have two strokes, i.e. an aspiration stroke in which the medium is aspirated from a reservoir and a compression stroke or delivery stroke where delivery of the metered medium e. g. into a metered line takes place. Diaphragm pumps known in the art for instance comprise suction check valves as well as discharge check valve to prevent back-flow. These check valves are usually spring biased and are opened and closed by the pressure difference of the medium to be pumped. The check valves are normally only operated by the differential pressure of the fluid. This compression spring exerts a comparatively low spring force in order to ensure that the check valve can easily be opened. This applies in particular to the check valve on the suction side of the pump.
There is a permanent need to increase the cost efficiency of diaphragm pumps, and to improve the dosing capabilities of diaphragm pumps.
It is therefore an object of the present invention to provide an improved diaphragm pump which offers an increased cost efficiency, further it is desirable to increase the dosing capabilities of the diaphragm pump.